In the performance of many process operations, it is necessary that a web of materials such, for example, as paper or photographic film or the like be passed through a treating station. In the course of performing the operation, the material is unwound from a first roll, passed through the station and then wound on another roll. To facilitate the performance of these operations, there are known in the prior art turrets, each of which includes a cross-shaft supporting two pairs of arms extending generally diametrically oppositely from the shaft and the arms of each pair being spaced axially of the shaft. One turret is provided at the unwinding location and a second turret at the winding location. Generally, one pair of arms at the unwinding turret supports a roll being unwound while the other pair of arms supports a fresh roll which is to be moved to the operating position when the roll being unwound is depleted. Similarly, at the winding station, one pair of arms supports a core being wound and the other pair of arms supports an empty core which is moved to the winding position when the roll being wound is complete. To shift the rolls between the two positions and to provide for replacement of a roll or of a core, the cross-shaft is supported for rotary movement on the turret frame. The weight of a full roll is approximately 12,000 pounds and this weight must be supported at various angular positions of the cross-shaft on the turret frame.
In most turrets of the prior art, the support arms customarily are permanently secured to the cross-shaft. Under certain conditions, it is necessary that the cross-arms support a roll of a different width than that for which the turret was specifically designed. While this might be accomplished by the use of a mandrel, it is desirable that the arms be able to be moved axially of the shaft so as to support rolls of various widths without employing a mandrel. To achieve this result in the prior art, the cross-shaft has been machined to a fine finish and the turret arms have been fitted with sleeves of a bearing material such, for example, as bronze, cast iron, or the like, to permit sliding movement of the arms on the shaft. In order that torque will be transmitted from the turret arm to the cross-shaft, a key and a key-way must be provided.
In addition to the foregoing, it is also desirable that the width setting of one pair of arms be different from that of the other pair. In the prior art construction, the arm bushings surround the cross-shaft; and interference between arms precludes large differential width settings. A third requirement for turrets adapted to handle webs of material is that the roll be shifted back and forth so as automatically to align the edge of the web into the process equipment. This involves a continuous back-and-forth motion of the arms. Owing to the very large loads involved, this motion causes rapid wear of the bushings and development of backlash after a relatively short period of time in use. The large loads require a large motor to overcome the friction which decreases the accuracy of guiding.
We have invented an improved turret for winding and unwinding operations which overcomes the defects of turrets of the prior art pointed out hereinabove. Our improved turret permits the arms to accommodate rolls of different widths without the use of a mandrel. It permits the arms of one pair to handle a roll of a highly differing width than that being handled by the other pair. Our turret permits of automatic side-lay adjustment without excessive friction affording a longer life in use.